Quantitative expression of LNAPL pollutant concentrations in capillary zone by coupling multiple environmental...

Area of Science:

• Environmental Science
• Hydrogeology
• Soil Science

Background:

• Light nonaqueous liquids (LNAPLs) are major soil and groundwater organic pollutants.
• Limited research exists on LNAPL concentration distribution in the capillary zone.
• Understanding LNAPL behavior in capillary zones is critical for environmental remediation.

Purpose of the Study:

• To investigate LNAPL concentration distribution in the silty sand capillary zone.
• To develop a quantitative model for LNAPL concentration using environmental factors.
• To assess the accuracy of the developed predictive model.

Main Methods:

• Conducted sandbox-migration experiments with diesel oil as the LNAPL.
• Monitored LNAPL (total petroleum hydrocarbon) concentration and environmental factors (moisture, EC, pH, ORP).
• Utilized a random forest algorithm to build a predictive model using 7744 data points.

Main Results:

• LNAPL concentration and environmental factors showed consistent patterns at similar heights.
• Distinct concentration variations were observed between 10.0-50.0 cm and above 60.0 cm from groundwater.
• The random forest model achieved R² > 0.90 and MAPE < 16.00% for training and test sets.

Conclusions:

• The developed model accurately quantifies and predicts LNAPL concentrations in the capillary zone.
• Environmental factors are key predictors of LNAPL distribution within capillary zones.
• This quantitative approach enhances understanding and management of LNAPL contamination.